The principal of Etiwanda High School was arrested early Tuesday for allegedly having a sexual relationship with a student.
Brian Garret Joseph, 38, and the student started the relationship when she was a minor and attending the high school, according to San Bernardino County sheriff's deputies.
Joseph resigned from his position at the Chaffey Joint Union High School District school on Tuesday after making bail.
Chaffey Joint Union officials contacted sheriff's deputies at the Rancho Cucamonga station to report that Joseph might be involved in a sexual relationship with a former student.
"We got an anonymous tip that was very recent and we acted on it immediately," Superintendent Mathew Holton said. "This is a very sad day."
The sheriff's Crimes Against Children Detail investigated the allegations.
Detectives said they learned Joseph has been involved with the former student -- who is now 18 years old -- and that it became sexual while she was a student at Etiwanda High.
A search warrant was served shortly after midnight at Joseph's home in the 14000 block of Parkwood Avenue in Corona.
Joseph was taken into custody on accusations of unlawful sexual intercourse with a minor. He was booked at the Central Detention Center in San Bernardino and released on bail.
Holton sent an email to district staffers addressing the allegations on Tuesday morning.
"Dr. Joseph voluntarily resigned and, as a result, we have asked Tom Mitchell, a former EHS principal, to provide his good leadership skills to EHS and to continue to support the students and staff during this time of transition," Holton wrote in the email.
Joseph was principal for four years and also served as assistant principal at Etiwanda High, Holton said.
Etiwanda High records show Joseph, who is married and has earned a doctorate degree, worked for the district for nine years.